JPH098175A - Shelf formation method and bonding of multilayer printed-circuit board - Google Patents

Abstract

PURPOSE: To obtain a shelf formation method in which a prinetd-circuit board with a multistage bonding shelf can be manufactured easily, in which a printed- wiring board used to mount a semiconductor chip or the like can be manufactured with high accuracy and at low costs and in which a printed-circuit board, for a pin-grid array, with a bonding shelf and a printed-circuit board for a ball-grid array can be manufactured with high accuracy and at low costs by making use of it. CONSTITUTION: In a shelf formation method for bonding of a multilayer printed- circuit board, a bonding terminal 15 is formed in advance in a multilayer printed-circuit board which has formed a circuit 7 at the inside, a resin layer 8 which is situated at the upper part of the terminal 15 in an inner layer 2 is then removed, an opening is formed, and a bonding shelf 12 in which the terminal 15 is exposed is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention wire-bonds a circuit terminal or bonding terminal of a printed circuit board having a multi-layer structure to an electronic component such as a semiconductor chip (hereinafter referred to as a semiconductor chip), so that the bonding terminal of the inner layer is exposed. A method of forming a bonding shelf.

[0002]

2. Description of the Related Art In recent years, with the diversification and high quality of printed circuit boards, the printed circuit boards are multi-layered and a part of the printed circuit board is opened, and a semiconductor chip or the like is mounted in the opening, and a wire is connected to the printed circuit board. Mounting methods for bonding are increasing. In particular, in a package such as a multi-chip module, a ball grid array, or a heat dissipation flat bag, these semiconductor chips and the like are often wire-bonded to a printed board.

Further, since the semiconductor chips and the like have a higher density and a larger number of pins, the required number of bonding wires for connecting to them also increases.
It is not possible to secure a sufficient number of bonding terminals with only the surface. Therefore, it is necessary to increase the density and the number of layers of the printed circuit board, and step-like bonding shelves in which the bonding terminals are exposed have been formed in each layer. This is the case, for example, in US Pat. No. 5,352,211 depicted in FIG. 1 which illustrates the prior art.

A conventional means for forming a bonding shelf on a printed circuit board is disclosed in, for example, Japanese Patent Publication No. 2-5014. B) One of them is illustrated in FIGS. 2A and 2B showing the conventional example in the publication, and it can be simplified as shown in FIGS. 9 to 13 of the present application.

That is, the substrate 25 of the base material 26 on which the circuit 27 is formed, and the other openings 30 having different sizes in advance,
A plurality of base materials 28 and 29 on which the circuits 31 and 31 and the circuits 32 and 33 are formed are prepared, and an adhesive sheet or a prepreg 34 is sequentially formed on the substrate 25 from the base material 28 having the smaller openings 30 and 31. To be laminated to form a multi-layer. As a result, the opening is formed in a stepwise shape near the central portion, so that the opening at the bottom is used as a cavity and the steps around the openings 30 and 31 are bonded to the bonding terminals 37 and 38.
Bonding shelves 35 and 36 having exposed portions are formed.
The respective circuits 27, 28, 28 are conducted by through holes or blind via holes (not shown).

(B) Further, the invention described in Japanese Patent Publication No. 2-5014 mentioned above mainly describes the difference from the above-mentioned a), and a plurality of base materials are provided on the same substrate as the above-mentioned a). In addition to stacking and forming multiple layers, an upper base material having no opening is stacked on the upper surface of the base material to seal the inside, and through holes and plating are applied to these stacked base materials, and finally an opening is formed in the upper base material. It was done like this.

[0007]

By the way, among the above-mentioned conventional means for forming a shelf for bonding, the one described in (a) is a method for forming a copper foil or a copper foil on a substrate when electroless copper plating or the like is applied to a through hole. There is a problem that plating deposits on the bonding terminals of the bonding shelf, and further on the wall surface of the bonding shelf and the insulator of the circuit.

On the other hand, in the one described in (b), since the opening is finally formed in the upper plate, it is possible to prevent unnecessary electroless plating from adhering to the copper foil or the bonding terminal on the substrate. However, similarly to the above-mentioned a), since the adhesive sheets and the prepregs are used for bonding the respective base materials, they are pressure-bonded and heat-cured by a high-pressure press, so that the following problems remain.

A) When the above-mentioned adhesive sheet or prepreg is pressure-bonded and heat-cured by a high-pressure press, the resin may exude to the opening side at each step, which may cause a contact failure of the bonding terminal. b) If the pressure at the time of crimping is reduced in order to prevent the resin from seeping out, the flow of the resin becomes insufficient and the circuit between layers is not filled up, which may cause problems in terms of quality and reliability. c) In addition, since each base material on which circuits and openings are formed in advance is laminated / multi-layered, high positioning accuracy is required when pasting,
Although they are stacked using positioning pins, etc., the density of conductor chips, etc. and printed circuit boards has increased, and more stringent positioning accuracy has been required, and the required positioning accuracy cannot be obtained, and the yield is decreasing. .

The present invention is intended to solve the problems of the conventional method for forming a shelf for bonding a multilayer printed circuit board. That is, an object of the present invention is to make it possible to easily manufacture a printed circuit board having multi-stage wire bonding shelves and to manufacture a printed circuit board on which semiconductor chips and the like are mounted with high precision and low cost, and thus to have a multi-stage bonding shelf. High precision for pin grid array printed boards and ball grid array printed boards.
It is to be able to manufacture at low cost.

[0011]

A method for forming a shelf for bonding a multilayer printed circuit board according to the present invention includes a circuit 7-
In the multi-layer printed circuit board on which the bonding layer 15 is formed, the bonding terminals 15- are formed in advance inside the multilayer structure, and then the resin layer 8- on the terminals 15- of the inner layer 2- is removed and opened. The bonding rack 12 is formed so that the terminal 15 is exposed.

In the above structure, the multi-layer structure is the same as that of the illustrated embodiment.
The layer structure is not limited to two and may be four or more. Further, in the case of forming a multilayer, the layers 2 may be sequentially formed and laminated on the substrate 1 (build-up method), or may be previously laminated by a conventional method for forming a multilayer board using a prepreg or the like.

The resin layer 8-of the inner layer 2 is preferably a fiber-resin composite containing organic fibers instead of glass fibers in order to facilitate later removal. However, the present invention is not limited to this, and a simple substance or a composite of various thermosetting / thermoplastic resins may be used, and a film or sheet may be used. Further, these resins may contain an inorganic filler to the extent that they are unsupported in the subsequent removal step.

The resin layer 8-is formed, for example, by applying resin.
Lamination, coating, laminating and the like may be used. In the case of stacking, the circuit 7- may be formed by simultaneously stacking a copper foil on the upper surface, but in other cases, the conductive layer may be formed by subsequent plating or pasting.

Bonding terminal 1 of inner layer 2 after multi-layering
The resin layer 8-on the upper part of 5- is removed and an opening 10-is formed between it and the bonding terminal 15-in the relative position.
The method of removing and opening the resin layer 8-is, for example, by machining or
It may be performed by chemical etching, laser processing, plasma processing, or the like. When the substrate 1 is also provided with the opening, a part thereof may be removed by the above-mentioned method, but cutting or punching may be carried out since accuracy is not so required.

The resin layer 8 above the bonding terminal 15
Is removed and an opening 10 is formed to form a bonding shelf 12 with the bonding terminal 15 exposed.

In the figure, 4 is a base material of the substrate 1, 5 is a circuit on its upper surface, 6 is a resin layer of the inner layer 2, 7 is a circuit on its upper surface, and 8 is a resin layer of the upper layer 3. Reference numeral 9 denotes a copper foil on the upper surface of which the circuit and the bonding terminal 16 will be formed later. However, when the resin is removed by etching or the like, this is left as the copper foil until the removal is completed. And can be used as a masking material. In this case,
The bonding shelf 7 and the lowermost copper foil 5 also serve as a masking material for preventing etching below. The effect is remarkable when etching by laser or plasma processing. Further, after removing the resin to form these shelves, gold plating or the like may be applied to finish the shelves for bonding or the like. Reference numerals 10 and 11 denote openings formed by removing the resin layer 8-. The lowermost opening can be used as a cavity for mounting the semiconductor chip 13 or the like later. Therefore, the opening may be finally formed by punching or the like.

[0018]

According to the method for forming a bonding shelf for a multilayer printed circuit board according to the present invention, in the multilayer printed circuit board having the circuit 7 formed therein as described above, the bonding terminal 15 is previously formed inside the multilayer structure. , Then inner layer 2
The resin layer 8-on the terminal 15-is removed and opened to form a bonding shelf 12-exposed of the terminal 15-.

Therefore, unlike the prior art in which each layer in which through holes are previously formed is laminated by heating and pressurizing a prepreg or an adhesive sheet therebetween, the resin exudes to the opening 10-side at each step. As a result, contact failure of the bonding terminal 15 can be prevented.

Further, unlike the conventional case, it is not necessary to lower the pressure at the time of crimping in order to avoid resin exudation, so that the resin is sufficiently flowed to fill each circuit 5, 7-, and the quality is improved.・ Highly reliable products can be obtained.

Further, unlike the conventional method of forming a circuit and an opening in advance and laminating and laminating a base material and the like, the part-fat layer 8-above the bonding terminal 15 of the inner layer 2-is removed to form the opening 10-.
Since it is formed, there is no need to worry about positioning / positioning accuracy when stacking / multilayering, manufacturing is easy, yield is improved, and cost is reduced.

Although it is desirable to use a fiber-resin composite containing organic fibers as the resin layer 8-,
When aramid fiber is used as the organic fiber, the adhesiveness with the resin is improved. In particular, when polyparaphenylene oxydiphenyl ether amide fiber is used, a product having high purity and further excellent adhesiveness with a resin is formed.

In order to remove and open the resin layer 8-, for example, mechanical processing, chemical etching, laser processing or plasma processing may be used as described above, but chemical etching, laser processing or plasma processing can be performed with high precision. 10- are formed. In particular, when a high energy laser called an impact laser among carbon dioxide lasers is used as the laser processing, it is easy to control the processing depth of the opening 10-, and the wall surface is less damaged and the accuracy is higher. Is finished.

[0024]

1 to 5 show an embodiment of a method for forming a shelf for bonding a multilayer printed board according to the present invention, which shows a three-layer structure including a board 1.

This printed circuit board comprises a substrate 1 having a base material 4 with a circuit 5, a resin layer 6, a circuit 7 and a bonding terminal 1.
5 and an upper layer 3 on which a circuit and a bonding terminal 16 are similarly formed later on the resin layer 8 (see FIG. 1), which are laminated / multi-layered (FIG. 2).
reference). The above-mentioned circuit formation may be performed by pattern etching not before lamination / multilayering but after it, and may be performed by an ordinary subtraction method or an additive method. You may form a layer.

The resin layer 8 above the bonding terminal 15 of the inner layer 2, that is, the resin layer 8 of the upper layer 3 and the resin layer 6 of the inner layer 2.
Is preferably a fiber-resin composite containing organic fibers without glass fibers. As the organic fiber, aramid fiber, polybenzimidazole fiber, polyetheretherketone fiber, polyester fiber or the like can be used. However, aramid fiber is desirable because of its good adhesiveness to resin, and it is optimal to use polyparaphenyleneoxydiphenyletheramide fiber because of its high purity and adhesiveness to resin.

Further, unlike the above, the resin layers 8 and 6 have a structure not containing fibers, and may be, for example, in the form of a film or a sheet, and various thermosetting resins or thermoplastic resins alone, or a combination thereof. It may be a complex. As the resin composition in this case, for example, an epoxy resin, a polyimide resin, a polysilane resin, or the like may be used.

After laminating / multilayering as described above, the inner layer 2
The resin layer 8-above the bonding terminal 15 is removed and opened. Here, subsequently, the resin layer 6 of the inner layer 2 is also opened by removing the central portion from the bonding terminal 15.
In this case, the resin layer in the upper layer is removed and opened in a larger area, and the peripheral portions of the upper and lower openings 11 and 10 are formed in a staircase shape. The opening 1 formed by removing the resin layer 6 of the inner layer 2
0 will be a cavity portion in which a semiconductor chip or the like 13 will be mounted later.

The means for removing and opening the resin layers 8 and 6 may be mechanical processing such as cutting or punching, chemical etching, laser processing or plasma processing, and chemical etching, laser processing or plasma processing. According to the above, highly accurate processing can be performed. As the laser processing, an excimer laser, a YAG (yttrium aluminum garnet) laser, a carbon dioxide gas laser or the like is used. In particular, an excimer laser or a carbon dioxide gas laser is used in order to control the processing depth and reduce the damage on the wall surface. It is best to use a high energy laser called an impact laser. Also in this case, it is preferable to adopt an ordinary masking method similarly to the chemical etching.

By removing and opening the resin layer 8 above the bonding terminal 15 of the inner layer 2, the bonding terminal 12 with the bonding terminal 15 of the inner layer 2 exposed is formed, and a multilayer printed board with a shelf for bonding is formed. It is formed. After that, the circuit and the bonding terminal 16 are formed also on the copper foil 9 of the upper layer 3, and as shown in FIG. 6, the semiconductor chip or the like 13 is mounted and the exposed bonding terminals 15 and 16 and the semiconductor chip or the like 13 are formed. Bonding with the wire 17 may be performed between the terminals and the sealing resin 18 may be filled.

Next, FIGS. 6 to 8 show an embodiment to which the method for forming a shelf for bonding a multilayer printed circuit board according to the present invention is applied. In this case as well, description will be made assuming that a three-layer structure is formed when the substrate is included.

The multilayer printed circuit board used here is also the same as that described in the first embodiment of the present invention. The circuit board 5 with the circuit 5 and the circuit board 7 and the bonding terminals 15 are formed on the resin layer 6. The inner layer 2 and the upper layer 3 on which the circuit and the bonding terminals 16 are to be formed later on the resin layer 8 are laminated and formed into a multilayer structure (see FIG. 1 above).
-See Figure 2.)

Also in this case, after the above-mentioned lamination / multi-layering, the resin layer 8 above the bonding terminal 15 of the inner layer 2 is removed and the opening 11 is formed, so that the bonding terminal 15 of the inner layer 2 is exposed. The shelf 12 is formed. The means for removing and opening the resin layer 8 may be the same as described above. Here, subsequently, the resin layer 6 of the inner layer 2 is removed at a portion closer to the center than the bonding terminal 15 to form an opening 10, and further an opening 19 slightly smaller than the opening 10 of the inner layer 2 is formed in the substrate 1 (see FIG. 6).

The removal and opening of the resin layers 8 and 6 may be carried out by the same means as shown in the previous embodiment, but the above accuracy is required to form the opening 19 in the substrate 1. Since it is not performed, machining such as cutting or punching may be performed. The peripheries of the openings 10, 11, and 19 are formed in a staircase shape, and the opening 19 at the lowermost stage becomes a cavity portion in which the semiconductor chip or the like 13 is mounted later.

After that, the circuit and the bonding terminals 16 are formed on the copper foil 9 of the upper layer 3, and the bonding terminals 22 are formed on the substrate 1, respectively, and from the rear surface of the substrate 1, another substrate such as an organic material, a ceramic material or a metal material is formed. Stick a base material such as. Here, a copper alloy plate 14 having good heat dissipation is attached (see FIG. 7).

Then, the semiconductor chip 13 or the like is mounted on the copper alloy plate 14 in the opening 19 of the substrate 1, and each bonding terminal 15, 16, 20 and the terminal portion of the semiconductor chip 13 or the like are wire-connected in the same manner as described above. After the bonding, the periphery of the semiconductor chip 13 is filled with the sealing resin 18. Further, by mounting the solder ball 21 on the solder pad on the upper layer 3,
A cavity down ball grid array is formed.

[0037]

As is apparent from the above, the method for forming a bonding shelf for a multilayer printed circuit board according to the present invention allows a printed circuit board with a bonding shelf to be manufactured easily, with high precision and at low cost. A printed circuit board for a pin grid array, a printed circuit board for a ball grid array, etc. using the same can be manufactured easily, with high accuracy, and at low cost.

That is, in the conventional method for manufacturing a printed circuit board of this type, since the board having the through holes is previously heated and pressure-bonded with the prepreg or the thermosetting adhesive sheet, the resin oozes out at the time of bonding. There is no contact between the bonding terminals on the shelf and there is no resin bleeding out, but the resin flow is not enough to fill the spaces between the circuits, which causes problems in quality and reliability. Since the substrates on which the layers are formed are laminated / multi-layered, if the density of semiconductor chips or printed boards is increased, the required positional accuracy cannot be obtained and the yield is reduced.

On the other hand, in the method for forming a bonding shelf for a multilayer printed circuit board according to the present invention, bonding terminals are formed in advance inside the multilayer structure, and then the resin layer on the inner terminals is formed. By removing and opening, a bonding shelf with exposed terminals is formed.

Therefore, unlike conventional ones,
It is possible to prevent the resin from bleeding out to the opening side at each step and the bonding terminal from causing a contact failure at the time of multilayering.

Further, unlike the conventional case, there is no need to reduce the pressure at the time of crimping in order to avoid resin exudation, so that the flow of resin can be sufficiently carried out to fill the spaces between the circuits, and in terms of quality and reliability. You can get the high one.

Further, unlike the conventional method in which a circuit or through holes are previously formed and laminated, the circuit is formed after the lamination, and the resin is removed to form the opening after the lamination, so that the lamination / multilayer is formed. There is no difficulty in positioning and positioning accuracy at the time of production, manufacturing is easy, yield is improved, and cost can be reduced.

Fibers containing organic fibers as the resin layer
When aramid fiber is used as the resin composite, especially as the organic fiber, the adhesiveness with the resin becomes good. Further, when polyparaphenylene oxydiphenyl ether amide fiber is used, a high quality printed circuit board having high purity and further excellent adhesiveness with a resin can be formed.

If chemical etching, laser processing, plasma processing, or the like is used to remove the resin after laminating / multilayering, the opening can be formed with high precision. In particular, when a high-energy laser called an impact laser among excimer lasers and carbon dioxide lasers is used as the laser processing, the processing depth and the wall surface of the opening can be finished with higher accuracy.

[Brief description of drawings]

FIG. 1 is an exploded enlarged vertical sectional view of a part of a multilayer printed circuit board used in an embodiment of the present invention.

FIG. 2 is an enlarged vertical sectional view of the multilayer printed circuit board shown in FIG.

FIG. 3 is an enlarged vertical cross-sectional view showing a state in which a resin layer above an inner layer bonding terminal is removed and opened.

FIG. 4 is an enlarged vertical cross-sectional view showing a state in which a resin layer in a portion near a center of an inner layer bonding terminal is removed and opened.

5 is an enlarged vertical cross-sectional view showing a state in which a semiconductor chip is mounted on the structure shown in FIG. 4, and resin sealing is performed after wire bonding.

FIG. 6 is an enlarged vertical cross-sectional view showing a state in which an opening is also provided in a substrate in an example to which the present invention is applied.

FIG. 7 is an enlarged vertical sectional view showing a state in which another base material is attached to the one shown in FIG.

8 is an enlarged vertical cross-sectional view showing a state in which a semiconductor chip is mounted on the structure shown in FIG. 7, resin bonding is performed after wire bonding, and solder balls are mounted.

FIG. 9 is an enlarged vertical sectional view of a part of a substrate used in conventional means.

FIG. 10 is an enlarged vertical sectional view of a part of a base material as an inner layer used in a conventional means.

11 is an enlarged vertical cross-sectional view of a state in which the inner layer shown in FIG. 2 is attached to the substrate shown in FIG.

FIG. 12 is an enlarged vertical sectional view of a part of a base material as an upper layer used in the conventional means.

13 is an enlarged vertical cross-sectional view of the state shown in FIG. 11 to which the outer layer shown in FIG. 12 is attached.

[Explanation of symbols]

1-Substrate 11-Opening 21-
Solder ball 2-Inner layer 12-Shelving for bonding 3-Upper layer 13-Semiconductor chip etc. 4-Base material 14-Base material 5-Circuit 15-Bonding terminal 6-Resin layer 16-Bonding terminal 7-Circuit 17-Wire 8-Resin Layer 18-Sealing resin 9-Copper foil 19-Opening 10-Opening 20-Bonding terminal

Claims (7)

[Claims] 1. In a multilayer printed circuit board having a circuit formed therein, a bonding terminal is previously formed inside the multilayer structure, and thereafter, a resin layer on the upper terminal of the inner layer is removed and an opening is formed. A method for forming a bonding shelf for a multi-layer printed circuit board, which comprises forming a bonding shelf for which terminals are exposed. 2. The method for forming a shelf for bonding a multilayer printed circuit board according to claim 1, wherein the resin layer of the inner layer contains an organic fiber. 3. The resin layer contains aramid fibers,
The method for forming a shelf for bonding a multilayer printed circuit board according to claim 1, 2. 4. The resin layer comprises a film or sheet,
The method for forming a shelf for bonding a multilayer printed circuit board according to claim 1. 5. The method for forming a shelf for bonding a multilayer printed board according to claim 1, wherein the resin layer of the inner layer is removed by chemical etching. 6. The method for forming a shelf for bonding a multilayer printed circuit board according to claim 1, wherein the resin layer of the inner layer is removed by laser processing. 7. The method for forming a shelf for bonding a multilayer printed circuit board according to claim 1, wherein the resin layer of the inner layer is removed by plasma processing.